Device for impregnating fibers with a defined fiber volume fraction

Abstract

The disclosure relates to an apparatus for impregnating fibers (1) with a matrix material, including a unit for soaking the fibers with the matrix material. A unit for setting the fiber content by volume (100) includes at least one opening (107) through which the soaked fibers (1) are guided. Each opening (107) includes a minimum opening cross section (111) dimensioned such that matrix material is removed such that the desired fiber content by volume is achieved. The disclosure furthermore relates to a method for impregnating fibers in the apparatus.

1 . An apparatus for impregnating fibers with a matrix material, comprising a unit for soaking the fibers with the matrix material, wherein a unit for setting the fiber content by volume which comprises at least one opening by way of which the soaked fibers are guided is included, wherein each opening at the minimum opening cross section thereof is dimensioned such that so much matrix material is removed that the desired fiber content by volume is achieved and the unit for setting the fiber content by volume comprises an upper part and a lower part and the opening is configured in each case partially in the lower part and partially in the upper part. 
     
     
         2 . The apparatus according to  claim 1 , wherein the cross-sectional area of the at least one opening in the unit for setting the fiber content by volume decreases in size in the running direction of the fibers in the operation. 
     
     
         3 . The apparatus according to  claim 1 , wherein each opening in the unit for setting the fiber content by volume has a maximum width and a maximum height, each corresponding to at least the diameter of a roving. 
     
     
         4 . The apparatus according to  claim 1 , wherein each opening in the unit for setting the fiber content by volume is adjustable. 
     
     
         5 . The apparatus according to  claim 1 , wherein the unit for setting the fiber content by volume comprises an upper part and a lower part, each having one clearance, wherein in the case of the unit for setting the fiber content by volume being fitted, the clearance in the lower part and the clearing in the upper part intersect one another, thus forming the opening, and the opening cross section is adjustable by the mutual relative position of the upper part and the lower part. 
     
     
         6 . The apparatus according to  claim 1 , wherein the unit for soaking the fibers comprises a bath for receiving the matrix material. 
     
     
         7 . The apparatus according to  claim 6 , wherein the apparatus comprises a lower part, in which the bath is received, and a lid for closing, wherein in the case of the lid being fitted, in each case one gap is configured between the lid and the lower part on those sides through which the fibers are guided into the apparatus and exit from the apparatus. 
     
     
         8 . The apparatus according to  claim 5 , wherein the upper part of the unit for setting the fiber content by volume is disposed on the lid, and the lower part of the unit for setting the fiber content by volume is disposed on the lower part of the apparatus for impregnating. 
     
     
         9 . The apparatus according to  claim 7 , wherein the lower part of the apparatus for impregnating has a face that is inclined in the direction of the bath, matrix material dripping from the fibers being able to run back into the bath by way of said inclined face. 
     
     
         10 . The apparatus according to  claim 7 , wherein a deflection unit by way of which the fibers in the case of the lid being fitted can be pushed into the bath is fitted to the lid. 
     
     
         11 . The apparatus according to  claim 5 , wherein a drip unit having at least one wiper having a wiping edge by way of which the soaked fibers are guided in the operation is included. 
     
     
         12 . The apparatus according to  claim 6 , wherein the unit for setting the fiber content by volume is designed and positioned such that said unit for setting the fiber content by volume by way of that side on which the fibers are fed is submerged in the bath and that side on which the fibers exit from the unit for setting the fiber content by volume lies outside the bath. 
     
     
         13 . The apparatus according to  claim 12 , wherein the unit for setting the fiber content by volume has a nozzle having the minimal cross section, said nozzle protruding into the matrix material, and a duct which adjoins the nozzle and through which the soaked fibers are guided and which terminates outside the matrix material. 
     
     
         14 . The apparatus according to  claim 12 , wherein the unit for setting the fiber content by volume is configured in a wall of the bath. 
     
     
         15 . The apparatus according to  claim 12 , wherein an opening for feeding the fibers is configured in the wall of the bath. 
     
     
         16 . The apparatus according to  claim 12 , wherein at least two wipers are received in the bath, said wipers in an alternating manner acting on the fibers from above and from below, wherein the wipers are in particular positioned such that the wiping edges of said wipers in operation lie below the liquid level of the matrix material. 
     
     
         17 . The apparatus according to  claim 1 , wherein deflection elements about which the fibers are guided are received in the bath. 
     
     
         18 . The apparatus according to  claim 1 , wherein an inflow and an outflow for a flushing gas are included. 
     
     
         19 . The apparatus according to  claim 1 , wherein a connection for the supply of matrix materials is included. 
     
     
         20 . A method for setting the fiber content by volume when impregnating fibers in an apparatus according to  claim 1 , said method comprising the following steps:
 (a) soaking the fibers with a matrix material;   (b) guiding the soaked fibers through the at least one opening of the installation for setting the fiber content by volume, wherein at least two fibers are guided through each opening of the unit for setting the fiber content by volume, and each opening has a minimum cross-sectional area which meets the following correlation:   
       
         
           
             
               A 
               = 
               
                 
                   n 
                   · 
                   Tex 
                 
                 
                   ϕ 
                   · 
                   ρ 
                 
               
             
           
         
       
       where
 n=number of fibers which in the operation are guided through the opening; 
 Tex=the fiber count Tex in g/1000 m; 
 φ=fiber content by volume; 
 ρ=density of the fibers. 
 
     
     
         21 . The method according to  claim 20 , wherein the fibers are carbon fibers, glass fibers, or aramid fibers. 
     
     
         22 . The method according to  claim 20 , wherein the matrix material is selected from unsaturated polyester resins, vinyl esters, epoxy resins, and polyurethanes, and the reactants thereof. 
     
     
         23 . The method according to  claim 20 , wherein the fibers prior to infeeding to the matrix material, or after infeeding to the matrix material, through an opening ( 59 ) in the wall of a bath which contains the matrix material are divided into individual fibers, groups of fewer fibers, or individual rovings, are guided about deflection element, and after the deflection elements are bundled again and are fed to the unit for setting the fiber content by volume. 
     
     
         24 . The method according to  claim 20 , wherein wipers by way of which the fibers are guided are provided in the bath, whereby the wiping edges of the wipers lie below the liquid level of the matrix material.